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Grulke EA, Wu X, Ji Y, Buhr E, Yamamoto K, Song NW, Stefaniak AB, Schwegler-Berry D, Burchett WW, Lambert J, Stromberg AJ. Differentiating gold nanorod samples using particle size and shape distributions from transmission electron microscope images. Metrologia 2018; 55:254-267. [PMID: 32410745 PMCID: PMC7224690 DOI: 10.1088/1681-7575/aaa368] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Size and shape distributions of gold nanorod samples are critical to their physico-chemical properties, especially their longitudinal surface plasmon resonance. This interlaboratory comparison study developed methods for measuring and evaluating size and shape distributions for gold nanorod samples using transmission electron microscopy (TEM) images. The objective was to determine whether two different samples, which had different performance attributes in their application, were different with respect to their size and/or shape descriptor distributions. Touching particles in the captured images were identified using a ruggedness shape descriptor. Nanorods could be distinguished from nanocubes using an elongational shape descriptor. A non-parametric statistical test showed that cumulative distributions of an elongational shape descriptor, that is, the aspect ratio, were statistically different between the two samples for all laboratories. While the scale parameters of size and shape distributions were similar for both samples, the width parameters of size and shape distributions were statistically different. This protocol fulfills an important need for a standardized approach to measure gold nanorod size and shape distributions for applications in which quantitative measurements and comparisons are important. Furthermore, the validated protocol workflow can be automated, thus providing consistent and rapid measurements of nanorod size and shape distributions for researchers, regulatory agencies, and industry.
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Affiliation(s)
- Eric A Grulke
- Chemical and Materials Engineering, University of Kentucky, Lexington, KY, United States of America
| | - Xiaochun Wu
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 1001901, People's Republic of China
| | - Yinglu Ji
- CAS Key Laboratory of Standardization and Measurement for Nanotechnology, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 1001901, People's Republic of China
| | - Egbert Buhr
- Physikalisch-Technische Bundesanstalt (PTB), Braunschweig, Germany
| | - Kazuhiro Yamamoto
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Nam Woong Song
- Korea Research Institute of Standards and Science (KRISS), Daejeon, Republic of Korea
| | - Aleksandr B Stefaniak
- US National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, United States of America
| | - Diane Schwegler-Berry
- US National Institute for Occupational Safety and Health (NIOSH), Morgantown, WV, United States of America
| | - Woodrow W Burchett
- Applied Statistics Laboratory, University of Kentucky, Lexington, KY, United States of America
| | - Joshua Lambert
- Applied Statistics Laboratory, University of Kentucky, Lexington, KY, United States of America
| | - Arnold J Stromberg
- Applied Statistics Laboratory, University of Kentucky, Lexington, KY, United States of America
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Raab M, Jusuk I, Molle J, Buhr E, Bodermann B, Bergmann D, Bosse H, Tinnefeld P. Using DNA origami nanorulers as traceable distance measurement standards and nanoscopic benchmark structures. Sci Rep 2018; 8:1780. [PMID: 29379061 PMCID: PMC5789094 DOI: 10.1038/s41598-018-19905-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 12/21/2017] [Indexed: 11/09/2022] Open
Abstract
In recent years, DNA origami nanorulers for superresolution (SR) fluorescence microscopy have been developed from fundamental proof-of-principle experiments to commercially available test structures. The self-assembled nanostructures allow placing a defined number of fluorescent dye molecules in defined geometries in the nanometer range. Besides the unprecedented control over matter on the nanoscale, robust DNA origami nanorulers are reproducibly obtained in high yields. The distances between their fluorescent marks can be easily analysed yielding intermark distance histograms from many identical structures. Thus, DNA origami nanorulers have become excellent reference and training structures for superresolution microscopy. In this work, we go one step further and develop a calibration process for the measured distances between the fluorescent marks on DNA origami nanorulers. The superresolution technique DNA-PAINT is used to achieve nanometrological traceability of nanoruler distances following the guide to the expression of uncertainty in measurement (GUM). We further show two examples how these nanorulers are used to evaluate the performance of TIRF microscopes that are capable of single-molecule localization microscopy (SMLM).
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Affiliation(s)
- Mario Raab
- Institute for Physical & Theoretical Chemistry, and Braunschweig, Integrated Centre of Systems Biology (BRICS) and Laboratory for Emerging Nanometrology (LENA), Braunschweig University of Technology, Rebenring 56, 38106, Braunschweig, Germany.,Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universitaet Muenchen, Butenandtstr, 5-13, 81377, Muenchen, Germany
| | - Ija Jusuk
- Institute for Physical & Theoretical Chemistry, and Braunschweig, Integrated Centre of Systems Biology (BRICS) and Laboratory for Emerging Nanometrology (LENA), Braunschweig University of Technology, Rebenring 56, 38106, Braunschweig, Germany.,Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universitaet Muenchen, Butenandtstr, 5-13, 81377, Muenchen, Germany
| | - Julia Molle
- Institute for Physical & Theoretical Chemistry, and Braunschweig, Integrated Centre of Systems Biology (BRICS) and Laboratory for Emerging Nanometrology (LENA), Braunschweig University of Technology, Rebenring 56, 38106, Braunschweig, Germany
| | - Egbert Buhr
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Bernd Bodermann
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Detlef Bergmann
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Harald Bosse
- Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116, Braunschweig, Germany
| | - Philip Tinnefeld
- Institute for Physical & Theoretical Chemistry, and Braunschweig, Integrated Centre of Systems Biology (BRICS) and Laboratory for Emerging Nanometrology (LENA), Braunschweig University of Technology, Rebenring 56, 38106, Braunschweig, Germany. .,Department of Chemistry and Center for NanoScience, Ludwig-Maximilians-Universitaet Muenchen, Butenandtstr, 5-13, 81377, Muenchen, Germany.
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Buhr E, Herrmann C, Hoeschen D. Correlation Between Physical Image Quality Parameters and Visually Perceptible Image Quality in X-Ray Diagnosis. ACTA ACUST UNITED AC 2016. [DOI: 10.1080/00223638.1993.11738493] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Yuana Y, Böing AN, Grootemaat AE, van der Pol E, Hau CM, Cizmar P, Buhr E, Sturk A, Nieuwland R. Handling and storage of human body fluids for analysis of extracellular vesicles. J Extracell Vesicles 2015; 4:29260. [PMID: 26563735 PMCID: PMC4643195 DOI: 10.3402/jev.v4.29260] [Citation(s) in RCA: 146] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 09/25/2015] [Accepted: 10/17/2015] [Indexed: 12/22/2022] Open
Abstract
Because procedures of handling and storage of body fluids affect numbers and composition of extracellular vesicles (EVs), standardization is important to ensure reliable and comparable measurements of EVs in a clinical environment. We aimed to develop standard protocols for handling and storage of human body fluids for EV analysis. Conditions such as centrifugation, single freeze-thaw cycle, effect of time delay between blood collection and plasma preparation and storage were investigated. Plasma is the most commonly studied body fluid in EV research. We mainly focused on EVs originating from platelets and erythrocytes and investigated the behaviour of these 2 types of EVs independently as well as in plasma samples of healthy subjects. EVs in urine and saliva were also studied for comparison. All samples were analysed simultaneously before and after freeze-thawing by resistive pulse sensing, nanoparticle tracking analysis, conventional flow cytometry (FCM) and transmission (scanning) electron microscopy. Our main finding is that the effect of centrifugation markedly depends on the cellular origin of EVs. Whereas erythrocyte EVs remain present as single EVs after centrifugation, platelet EVs form aggregates, which affect their measured concentration in plasma. Single erythrocyte and platelet EVs are present mainly in the range of 100-200 nm, far below the lower limit of what can be measured by conventional FCM. Furthermore, the effects of single freeze-thaw cycle, time delay between blood collection and plasma preparation up to 1 hour and storage up to 1 year are insignificant (p>0.05) on the measured concentration and diameter of EVs from erythrocyte and platelet concentrates and EVs in plasma, urine and saliva. In conclusion, in standard protocols for EV studies, centrifugation to isolate EVs from collected body fluids should be avoided. Freezing and storage of collected body fluids, albeit their insignificant effects, should be performed identically for comparative EV studies and to create reliable biorepositories.
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Affiliation(s)
- Yuana Yuana
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Anita N Böing
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Anita E Grootemaat
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Edwin van der Pol
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
- Department of Biomedical Engineering and Physics, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Chi M Hau
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Petr Cizmar
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
| | - Egbert Buhr
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany
| | - Auguste Sturk
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Rienk Nieuwland
- Department of Clinical Chemistry, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands;
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Andres H, Lüönd F, Schlatter J, Auderset K, Jordan-Gerkens A, Nowak A, Ebert V, Buhr E, Klein T, Tuch T, Wiedensohler A, Mamakos A, Riccobono F, Discher K, Högström R, Yli-Ojanperä J, Quincey P. Measuring soot particles from automotive exhaust emissions. EPJ Web of Conferences 2014. [DOI: 10.1051/epjconf/20147700020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Bosse H, Koenders L, Härtig F, Buhr E, Wilkening G. Nano- and micrometrology at PTB: State of the art and future challenges. ACTA ACUST UNITED AC 2010. [DOI: 10.3103/s8756699010040023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Samei E, Buhr E, Granfors P, Vandenbroucke D, Wang X. Comparison of edge analysis techniques for the determination of the MTF of digital radiographic systems. Phys Med Biol 2005; 50:3613-25. [PMID: 16030386 DOI: 10.1088/0031-9155/50/15/009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The modulation transfer function (MTF) is well established as a metric to characterize the resolution performance of a digital radiographic system. Implemented by various laboratories, the edge technique is currently the most widespread approach to measure the MTF. However, there can be differences in the results attributed to differences in the analysis technique employed. The objective of this study was to determine whether comparable results can be obtained from different algorithms processing identical images representative of those of current digital radiographic systems. Five laboratories participated in a round-robin evaluation of six different algorithms including one prescribed in the International Electrotechnical Commission (IEC) 62220-1 standard. The algorithms were applied to two synthetic and 12 real edge images from different digital radiographic systems including CR, and direct- and indirect-conversion detector systems. The results were analysed in terms of variability as well as accuracy of the resulting presampled MTFs. The results indicated that differences between the individual MTFs and the mean MTF were largely below 0.02. In the case of the two simulated edge images, all algorithms yielded similar results within 0.01 of the expected true MTF. The findings indicated that all algorithms tested in this round-robin evaluation, including the IEC-prescribed algorithm, were suitable for accurate MTF determination from edge images, provided the images are not excessively noisy. The agreement of the MTF results was judged sufficient for the measurement of the MTF necessary for the determination of the DQE.
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Affiliation(s)
- Ehsan Samei
- Duke Advanced Imaging Laboratories, Departments of Radiology, Biomedical Engineering, and Physics, Duke University, DUMC 3302, Durham, NC 27710, USA
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Illers H, Hoeschen C, Buhr E. Messung des detektiven Quantenwirkungsgrades (DQE) für einen direkten und zwei indirekte Flächendetektoren sowie einen CR-Detektor. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-868266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Hoeschen C, Tischenko O, Buhr E, Jungnickel K. Vereinfachtes Verfahren zur Bestimmung der Korrekturbilder bei Flächendetektoren. ROFO-FORTSCHR RONTG 2005. [DOI: 10.1055/s-2005-867583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Verdun FR, Pachoud M, Bergmann D, Buhr E. Assessment of radiographic screen-film systems: a comparison between the use of a microdensitometer and a drum film digitiser. Radiat Prot Dosimetry 2005; 114:208-13. [PMID: 15933110 DOI: 10.1093/rpd/nch563] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A high-end drum film digitiser (Tango, Germany) and a calibrated linear microdensitometer developed by PTB were used to assess the modulation transfer function (MTF) and the noise power spectra (NPS) of 3 mammographic screen film systems at optical density levels of 0.8, 1.5 and 2.5. The use of a drum scanner to assess MTF and NPS data appears to be adequate but requires an appropriate characterisation of the scanner to verify its internal noise level and its MTF. It is further necessary to calibrate the scanner output in terms of visual diffuse optical densities. Processing of two-dimensional digital data of grating images need to be more strictly defined for accurate MTF measurements of screen-film systems. Nevertheless, even now it seems to be feasible to use commercially available high-end and well calibrated scanners to assess screen film systems. This is especially important for quality assurance purposes because important parameters of screen film systems such like MTF and NPS can now be determined without using sophisticated microdensitometers which are not commercially available.
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Affiliation(s)
- F R Verdun
- University Institute for Applied Radiophysics, Grand-Pré 1, CH-Lausanne, Switzerland.
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Illers H, Buhr E, Hoeschen C. Measurement of the detective quantum efficiency (DQE) of digital X-ray detectors according to the novel standard IEC 62220-1. Radiat Prot Dosimetry 2005; 114:39-44. [PMID: 15933079 DOI: 10.1093/rpd/nch507] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A mobile measurement facility which complies with IEC 62220-1 has been set up to determine the detective quantum efficiency (DQE) of digital X-ray detector systems. Exemplary measurements were performed for two similar CR detector systems, a CsI-based indirect detector and an Se-based direct detector. The standardised radiation quality RQA 5 was applied for measurement and for three of these systems RQA 9 was also applied. A pronounced dependence of DQE on radiation quality was observed for the direct detector, where the DQEs for RQA 5 and RQA 9 differ by a factor of approximately 2. The uncertainty (95% confidence interval) associated with the measured DQE values is within 0.01 and 0.04 depending on, for example, the spatial frequency. Thus, it has been demonstrated that the DQE can be measured accurately and reliably with the accuracy required by the international standard IEC 62220-1. It is now possible to objectively measure and compare DQE values of digital X-ray detector systems.
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Affiliation(s)
- Hartmut Illers
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany.
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Moores BM, Mattsson S, Månsson LG, Panzer W, Regulla D, Dance D, Alm Carlsson G, Verdun FR, Buhr E, Hoeschen C. RADIUS--closing the circle on the assessment of imaging performance. Radiat Prot Dosimetry 2005; 114:450-7. [PMID: 15933154 DOI: 10.1093/rpd/nch515] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The RADIUS (Radiological Imaging Unification Strategy) project addresses the assessment of image quality in terms of both physical and clinically relevant measures. The aim is to unify our understanding of both types of measure as well as the numerous underlying factors that play a key role in the assessments of imaging performance. In this way it is expected to provide a solid basis for the improvement in radiological safety management, where not only radiation risks are considered but also diagnostic risks of incorrect clinical outcomes (i.e. false positive/false negative). The project has applied a variety of relevant experimental and theoretical methods to this problem, which is generic to medical imaging as a whole. Digital radiography of the chest and the breast has been employed as the clinical imaging domain vehicles for the study. The project addressed the problem from the following directions: role and relevance of pathology, human observer studies including receiver operating characteristics, image quality criteria analysis, structural noise analysis, physical measurements on clinical images, physical measurements on imaging system, modelling of imaging system, modelling of visual processes, modelling of doses delivered and IT-based scientific support strategies. This paper presents an overview of the main outcomes from this project and highlights how the research outcomes actually apply to the real world. In particular, attention will be focused on new and original findings and methods and techniques that have been developed within the framework of the project. The relevance of the project's outcomes to future European research will also be presented.
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Affiliation(s)
- B M Moores
- Integrated Radiological Services Ltd, Unit 188 Century Buildings, Tower Street, Brunswick Business Park, Liverpool L3 4BJ, UK.
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Abstract
The X-ray pattern of a mass of very fine non-distinguishable anatomical structures alters completely from radiograph to radiograph due to the unavoidable movements of the patient during the exposure. The corresponding image component shows noise-like behaviour and is therefore referred to as the anatomical noise. Reducing this component would enhance the quality of the clinical X-ray image and increase the detectability of radiological signal. We have found that by comparing two X-ray images of the same anatomy acquired under slightly different imaging geometry, it is possible to reduce the anatomical noise in one of the image pair. The proposed method, which allows this, is based on the appropriate attenuation in the wavelet domain. The values of attenuating factors for the wavelet coefficients are proportional to the correlation between the corresponding features of both images. This method was tested for different changes in the imaging geometry. In the case of no geometrical changes, only the quantum and the electronic noise are reduced. An effect of de-noising for the investigated images is obvious.
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Affiliation(s)
- Oleg Tischenko
- Institute of Radiation Protection, Ingolstaedter Landstr. 1, 85764 Neuherberg, Germany.
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Illers H, Buhr E, Günther-Kohfahl S, Neitzel U. Measurement of the modulation transfer function of digital X-ray detectors with an opaque edge-test device. Radiat Prot Dosimetry 2005; 114:214-9. [PMID: 15933111 DOI: 10.1093/rpd/nch506] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
A variant of the edge method for the determination of the pre-sampled modulation transfer function (MTF) of digital X-ray imaging devices has been developed and accepted as the standard method in the novel DQE measurement standard IEC 62220-1. An opaque tungsten edge-test device accomplishes the ideal step-like profile of the incident X rays. The edge spread function is measured over a large region across the edge transition that enables an accurate MTF measurement including the 'low-frequency drop'. The method has been applied to different state-of-the-art X-ray imaging detectors, a computed radiography, a CsI-based indirect and an Se-based direct flat-panel detector. The MTF measurement results will be presented. In contrast to the opaque edge device, the commonly used semi-transparent edge-test devices produce scatter radiation that deteriorates the incident X-ray profile, which leads to a systematic overestimation of the MTF.
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Affiliation(s)
- Hartmut Illers
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany.
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Hoeschen C, Tischenko O, Buhr E, Illers H. Comparison of technical and anatomical noise in digital thorax X-ray images. Radiat Prot Dosimetry 2005; 114:75-80. [PMID: 15933084 DOI: 10.1093/rpd/nch543] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Former studies by Hoeschen and Buhr indicated a higher total noise in a thorax image than expected from technical noise, i.e. quantum and detector noise. This difference results from the overlay of many small anatomical structures along the X-ray beam, which leads to a noise-like appearance without distinguishable structures in the projected image. A method is proposed to quantitatively determine this 'anatomical noise' component, which is not to be confused with the anatomical background (e.g. ribs). This specific anatomical noise pattern in a radiograph changes completely when the imaging geometry changes because different small anatomical structures contribute to the projected image. Therefore, two images are taken using slightly different exposure geometry, and a correlation analysis based on wavelet transforms allows to determining the uncorrelated noise components. Since the technical noise also differs from image to image, which makes it difficult to separate the anatomical noise, images of a lung phantom were produced on a low-sensitive industrial X-ray film using high-exposure levels. From these results, the anatomical noise level in real clinical thorax radiographs using realistic exposure levels is predicted using the general dose dependence described in the paper text and compared with the quantum and detector noise level of an indirect flat-panel detector system. For consistency testing, the same lung phantom was imaged with the same digital flat-panel detector and the total image noise including anatomical noise is determined. The results show that the relative portion of anatomical noise may exceed the technical noise level. Anatomical noise is an important contributor to the total image noise and, therefore, impedes the recognition of anatomical structures.
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Affiliation(s)
- Christoph Hoeschen
- Department for Diagnostic Radiology, University Hospital Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany.
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Neitzel U, Buhr E, Hilgers G, Granfors PR. Determination of the modulation transfer function using the edge method: Influence of scattered radiation. Med Phys 2004; 31:3485-91. [PMID: 15651631 DOI: 10.1118/1.1813872] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The edge method for measuring the modulation transfer function (MTF) has recently gained popularity due to its simplicity and appropriateness particularly for digital imaging systems. Often edge test devices made of rather thin metal sheets are used, which are semitransparent to x rays and may generate scattered radiation. The effect of this scattered radiation on the determined MTF was investigated both theoretically (assuming an ideal detector) and experimentally using a CsI-based digital detector. It was found that the MTF increases due to the scattered radiation for all spatial frequencies larger than 0 mm(-1). The theoretical model developed in this study predicts that the maximum error compared to the true detector MTF is given by S/A, where A is the attenuated fraction and S is the scattered fraction reaching the detector, relative to the incident radiation. Theoretical and experimental results are in good agreement for radiation qualities corresponding to general radiography (RQA3, RQA5, and RQA7), whereas for chest beam quality (RQA9) the experimentally observed MTF error is larger than predicted by the simple model, possibly because the energy response of the CsI-based detector differs from that of an ideal one. The theoretical MTF error reaches a value of 18% for a 0.25 mm thick lead edge of RQA9. Since the MTF enters squared into the determination of the detective quantum efficiency (DQE), an error of at least 36% in DQE may result when using this edge test device. In conclusion, the use of fully absorbing edge material is advised for MTF determination with the edge method.
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Affiliation(s)
- Ulrich Neitzel
- Philips Medical Systems, Röntgenstrasse 24, D-22335 Hamburg, Germany.
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Tischenko O, Hoeschen C, Redlich U, Reissberg S, Buhr E, Döhring W. Reduktion des Quanten- und Elektronikrauschens in der CR- Projektionsradiographie. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-827908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Hoeschen C, Buhr E, Illers H, Bergmann D, Tischenko O, Richter C, Döhring W. Messungen der physikalischen Bildqualitätsparameter entsprechend IEC 62220–1 an einem direkten und einem indirekten Flächendetektor. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-827716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Hoeschen C, Tischenko O, Buhr E, Döhring W. Verlustfreie Dosisreduktion durch intelligente Rauschunterdrückung in der diagnostischen Anwendung von Röntgenstrahlung. ROFO-FORTSCHR RONTG 2004. [DOI: 10.1055/s-2004-827989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Buhr E, Günther-Kohfahl S, Neitzel U. Accuracy of a simple method for deriving the presampled modulation transfer function of a digital radiographic system from an edge image. Med Phys 2003; 30:2323-31. [PMID: 14528954 DOI: 10.1118/1.1598673] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Several methods for accurately deriving the presampled modulation transfer function (MTF) of a pixelated detector from the image of a slightly slanted edge have been described in the literature. In this paper we report on a simple variant of the edge method that produces sufficiently accurate MTF values for frequencies up to the Nyquist frequency limit of the detector with little effort in edge alignment and computation. The oversampled ESF is constructed in a very simple manner by rearranging the pixel data of N consecutive lines corresponding to a lateral shift of the edge by one pixel. A regular subsampling pitch is assumed for the oversampled ESF, which is given by the original pixel sampling distance divided by the integer number N. This allows the original data to be used for further computational analysis (differentiation and Fourier transform) without data preprocessing. Since the number of lines leading to an edge shift by one pixel generally is a fractional number rather than an integer, a systematic error may be introduced into the presampled MTF. Simulations and theoretical investigations show that this error is proportional to 1/N and increases with spatial frequency. For all frequencies up to the Nyquist limit, the relative error delta MTF/MTF is smaller than 1/(2N). It can thus be kept below a given threshold by suitably selecting N, which furnishes a certain maximum edge angle. The method is especially useful for applications where the presampled MTF is needed only for frequencies up to the Nyquist frequency limit, such as the determination of the detective quantum efficiency (DQE).
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Affiliation(s)
- Egbert Buhr
- Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany
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Abstract
The effects of different film processing conditions on light and x-ray sensitometric responses were compared for a variety of double-emulsion x-ray films. The processing conditions were altered by changes of the developer temperature. Three different exposure variants were applied: x-ray sensitometry using two stepped neutral density attenuators between film and screens, simultaneous double-sided light sensitometry, and single-sided light sensitometry. 13 different types of double-emulsion x-ray films were investigated, among them three asymmetric films. In the special case of exposing the asymmetric films with the single-sided light sensitometer, a method was investigated where each side of the film is exposed at different locations and the sum effect is analyzed. From each sensitometric curve shape two parameters, the logarithmic speed (logS) and the average gradient (G), were evaluated. The results of this study can be summarized as follows: (1) Single-sided and double-sided light sensitometers revealed almost equal changes of logS when the processing conditions are altered. Thus, single-sided light sensitometers can serve as a substitute for double-sided light sensitometers provided that suited exposure methods are used and appropriate sensitometric parameters are evaluated. (2) Light sensitometry quantitatively indicated changes of the film processing that affect the x-ray speed. Hence, light sensitometry is a useful method to monitor changes in film processing.
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Affiliation(s)
- C Blendl
- University of Applied Sciences, Cologne, Germany.
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Buhr E, Bergmann D, Hoeschen D, Ailliet M, Sirand-Rey G, Gazzola C, Uras S. An interlaboratory measurement of screen-film speed and average gradient according to ISO 9236-1. Med Phys 2000; 27:307-11. [PMID: 10718133 DOI: 10.1118/1.598832] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
The speed and average gradient of a conventional screen-film system was measured at four European laboratories. This is the first interlaboratory comparison in which the measurement conditions described in ISO 9236-1 were applied. The four laboratories used calibrated measurement equipment. The values obtained by the four laboratories were within a range of 14% for the speed and within a range of 8% for the average gradient. These variations are consistent with the expected measurement uncertainty.
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Affiliation(s)
- E Buhr
- Physikalisch-Technische Bundesanstalt, Braunschweig, Germany.
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Hoeschen D, Buhr E. [Acceptance test of film processing in roentgen diagnosis]. Aktuelle Radiol 1996; 6:203-5. [PMID: 8924456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In radiological acceptance tests, the film processing settings are verified by means of light sensitometry. The preliminary standard DIN 6868-55 probably published in August 1996 standardizes this procedure. This standard, its legal relevance and the sensitometer specifications are discussed. An outlook to the future development of the procedure as regards both the necessary technical progress and the establishment of a hierarchical metrological structure is included.
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Affiliation(s)
- D Hoeschen
- Physikalisch-Technische Bundesantalt, Braunschweig
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Abstract
The visual observer performance for detecting low-contrast patterns by employing both the receiver operating characteristic (ROC) and the 9-alternative forced choice (9-AFC) method is investigated. For each observer and each experimental technique, the results were reproducible with respect to a repeated observation. When the results of different observers for each method are compared, a strong variation of values is found. From the ROC data obtained, the expected percentages of correct detection in a 9-AFC experiment is calculated and compared with the corresponding values of the actual 9-AFC experiment. For some observers, the latter values were significantly higher than the computed ones, whereas for others the results showed good agreement with predictions from theory.
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Affiliation(s)
- C Herrmann
- Physikalisch-Technische Bundesanstalt, Braunschweig, Federal Republic of Germany
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Tamm C, Buhr E, Mlynek J. Raman heterodyne studies of velocity diffusion effects in radio-frequency-laser double resonance. Phys Rev A Gen Phys 1986; 34:1977-1994. [PMID: 9897483 DOI: 10.1103/physreva.34.1977] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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